228 Dr. J. T. Cash. 



The quotation of one experiment will illustrate these facts suffi- 

 ciently. 



Experiment VIII, Curve VII. — Travelling Sound in Upper Fistulous 

 Opening (quick drum). 



a. Peristalsis on introduction of large sound (before feeding). 



1. „ „ (after „ ). 



c. „ in advanced stage of digestion. 



„ Lower line indicates respiration. 



Experiment VIII (Curve VII, a, b, c). — Dog fasting sixteen hours. 

 Large travelling sound (9 X 18 mm.) introduced into upper fistulous 

 opening. Record on drum of medium velocity. 



0'. In 80" succeeding introduction of sound twenty-three contrac- 

 tions occur (a). Average length of each contraction Z'Z". 

 Total advance of sound 28 mm. Sound removed. 



5'. Full meal of meat given to dog. 

 35'. Sound again placed in upper opening. (Slight irregularity in 

 curves caused by tremor of animal, which often occurred for a 

 time after meal, and to a lesser extent by respiratory move- 

 ments.) In 80" succeeding introduction of sound, fourteen 

 contractions occur (6). Average length of "forwarding" 

 peristaltic waves 5". Average length of two contractions 

 succeeded by a more complete relaxation occurring in the 

 middle of tracing 33". 



Actual advance of sound 38 mm. 

 4 hours. At time of registration contractions take place at the rate 

 of six and a half in 80". Sound advances at rate of 10 mm. in 

 80" (c). Contractions which are long maintained recur for 

 20" to 60", and are succeeded by pauses of several minutes' 

 duration. 



This change in the rhythm, character, and potentiality of the 

 peristaltic contractions shows how extensive the range of adaptation 

 of these movements to the necessities of the time must be. 



